1. Field of the Invention
The present invention relates to a face position detection method and a face position detection apparatus, and an exposure method and an exposure apparatus, a production method for an exposure apparatus and a production method for a semiconductor device, used in an exposure step in, for example, thin-film magnetic head production.
2. Description of the Related Art
Heretofore, various exposure apparatus have been used when manufacturing thin-film magnetic heads, semiconductor devices or liquid crystal display devices by a photolithography process. Presently however, exposure apparatus are typically being used, which transfer a pattern image formed on a photo mask or a reticle (hereinafter, referred to as a xe2x80x9cmaskxe2x80x9d) onto a substrate, on the surface of which a photosensitive material such as a photoresist or the like is applied, via a projection optical system.
Recently, with a pattern projected onto an exposure area (shot area) on the substrate being made minute, the numerical aperture NA of the projection optical system of the exposure apparatus is set large, and as a result, the depth of focus of the projection optical system becomes shallow. Therefore, such an exposure apparatus is provided with an auto focus mechanism for adjusting the position of the substrate projection optical system in the direction of the optical axis, and a leveling mechanism for adjusting the inclination of the substrate with respect to the optical axis, in order to accommodate the exposure area on the substrate within the depth of focus of an imaging plane (focal position) of the projection optical system.
The auto focus leveling mechanism comprises, as an example, a beam irradiation system for irradiating beams onto a plurality of measurement points on the exposure area on the substrate, from an inclined direction with respect to the optical axis of the projection optical system for projecting, for example, an image of a slit pattern serving as a probe pattern, and a beam photodetecting system for receiving reflected light of the image on the plurality of probe patterns and re-imaging the image on the photodetector. Then, after the position of the exposure area on the substrate with respect to the focal position of the projection optical system, and the inclination of the exposure area on the substrate with respect to the optical axis have been detected, based on the detection signals of the beam photodetecting system corresponding to the plurality of measurement points, the exposure area on the substrate is subjected to positional adjustment in the direction of the optical axis (focal position adjustment) and inclination adjustment with respect to the optical axis (leveling adjustment) of the projection optical system.
The focal position adjustment and the leveling adjustment are performed by comparing a position of the probe pattern image on the photodetector which changes when the exposure area on the substrate is moved in the direction of the optical axis of the projection optical system or the exposure area on the substrate is inclined with respect to the optical axis, and a position of the probe pattern image pre-determined at the time of arranging the exposure area on the substrate at a focal position of the projection optical system, and moving a table on which the substrate is mounted in the direction of the optical axis of the projection optical system or inclining the table with respect to the optical axis thereof, so that the amount of discrepancy between these images is within a predetermined range. In this case, the focal position adjustment is performed based on, for example, the average value of respective detection signals corresponding to all the measurement points, and the leveling adjustment is performed so as to match the substrate with the least squares approximation plane for the respective detection signals. That is to say, the focal point adjustment and the leveling adjustment are performed with respect to all the plurality of measurement points on the substrate. Then, a pattern image of the mask is projected onto the substrate having been subjected to the focal point adjustment and the leveling adjustment via the projection optical system, to thereby form a pattern on the surface.
The pattern to be formed on the substrate in this manner is formed by repeating lithography steps such as exposure, development and the like, while changing a plurality of masks, and is in a rectangular shape having a stepped portion comprising a plurality of layers. In this case, particularly in a production process for thin-film magnetic heads for a magnetic disk apparatus, there may be a case where the difference of elevation (of the stepped portion comprising the plurality of layers) between the substrate surface and the thin-film magnetic head is relatively large, for example, 10 to 20 xcexcm. When a beam for detecting the face position is irradiated onto the substrate having a pattern with low flatness, the beam may be irradiated at a time so as to span over the concave and convex portions in the stepped portion. Since the reflected light of the beam at that time is not stable, then in particular, the position of the exposure area on the substrate with respect to the focal position of the projection optical system cannot be detected with high precision.
Moreover, the focal position adjustment is performed based on the average value of the detection signals corresponding to all the plurality of measurement points. Hence, the precision of the focal position adjustment in a certain area on the substrate decreases. That is to say, if the focal position adjustment is performed with respect to a pattern having, for example, a large stepped portion, the focal position of the projection optical system does not coincide with the concave portion or convex portion in the stepped portion. Therefore, when a focus is to be adjusted only on the concave portion or the convex portion, focal position adjustment cannot be performed with high precision. Moreover, since the focal position adjustment and the leveling adjustment is performed using detection signals corresponding to all the plurality of measurement points, the processing time for calculating the optimum position of the substrate in the direction of the optical axis and the optimum inclination angle with respect to the optical axis becomes long.
On the other hand, such a pattern is formed by overlapping a plurality of layers by means of a multiplicity of exposures using a plurality of masks. However in this case, the substrate thermally expands due to heating from the exposure light. Hence there may be a case where the layers cannot be overlapped with high precision.
In view of the above situation, it is an object of the present invention to provide a face position detection method and a face position detection apparatus which can perform detection of the face position of a substrate with high precision, even when a pattern having a large stepped portion is formed by means of a plurality of layers on the surface of the substrate, and an exposure method and an exposure apparatus, a production method for the exposure apparatus and a production method for a semiconductor device.
To solve the above described problems, the present invention adopts the following constructions associated with FIG. 1 to FIG. 6 showing an the embodiment.
A face positional information detection method of the present invention is a method for detecting face positional information for the surface of an object (W), comprising steps for: irradiating measurement beams (S1 to S9) onto a plurality of places on the surface of an object; detecting the plurality of measurement beams from the surface of the object; and determining face positional information for the surface of the object based on the detection results for the plurality of measurement beams, and is characterized in that, in the step for irradiating the measurement beams, at least either one of the shape and size of at least one (S9) of the plurality of measurement beams on the surface of the object is smaller than at least either one of the shape and size of the other measurement beams (S1 to S8) on the surface of the object. According to the present invention, even if there is formed a stepped portion on the surface of the object (W), the measurement beam (S9), at least either one of the shape and size of which is set to be small, is irradiated so as to avoid the stepped portion. Therefore, the face position can be detected with high precision, without being affected by the stepped portion.
Such a face position detection method is realized by a face position detection apparatus having an irradiation system (4) for irradiating measurement beams onto a plurality of places on the surface of the object (W), and a detection system (5) arranged in a predetermined positional relationship to the irradiation system, for detecting the plurality of measurement beams from the surface of the object, and characterized in that in the irradiation system at least either one of the shape and size of at least one (S9) of the plurality of measurement beams on the surface of the object is smaller than at least either one of the shape and size of the other measurement beams (S1 to S8) on the surface of the object.
Then, by detecting the position of the surface of the object (W) with respect to a predetermined reference position, using at least one measurement beam (S9), the position of the surface of the object (W) with respect to the reference position is detected with high precision by the measurement beam irradiated so as to avoid the stepped portion. Moreover, by detecting the inclination of the surface of the object (W) with respect to a predetermined reference surface, using the other measurement beams (S1 to S8), the inclination of the surface of the object can be detected with high precision, based on the information for the plurality of points on the surface of the object (W). At that time, by arranging the at least one measurement beam approximately in the center of the plurality of measurement beams irradiated onto the surface of the object (W), the positional detection of the surface of the object (W) with respect to the reference position can be performed with high precision at a position approximately in the center on the surface of the object (W).
At the time of detecting the face positional information, by irradiating the at least one measurement beam (S9) onto at least one flat portion (100) formed on the surface of the object (W) beforehand, adverse effects on the face position detection due to the stepped portion can be effectively prevented. Therefore, face position detection can be performed with high precision. In this case, by setting the irradiation area of the at least one measurement beam (S9) on the surface of the object (W) to be smaller than the area of the flat portion (100), adverse effects on the face position detection due to the stepped portion can be reliably prevented. Therefore, face position detection, and in particular, position detection of the object face with respect to the reference position, can be performed with high precision.
A first exposure method according to the present invention is a method for exposing a substrate by projecting onto the substrate (W) a pattern image formed on a mask (M), comprising steps for: irradiating measurement beams (S1 to S9) onto a plurality of places on a substrate; detecting the plurality of measurement beams from the substrate; and adjusting the relative position of the projected image of the pattern and the substrate based on the detection result, and is characterized in that, in the step for irradiating the measurement beams, at least either one of the shape and size of at least one (S9) of the plurality of measurement beams on the surface of the object is smaller than at least either one of the shape and size of the other measurement beams (S1 to S8) on the surface of the object. According to the first exposure method, even if there is formed a stepped portion on the surface of the object (W), the measurement beam (S9), at least either one of the shape and size of which is set to be small, is irradiated so as to avoid the stepped portion.
The first exposure method is realized by a first exposure apparatus for exposing a substrate (W) by projecting onto the substrate a pattern image formed on a mask (M), having an irradiation system (4) for irradiating measurement beams (S1 to S9) onto a plurality of places on a substrate, and a detection system (5) arranged in a predetermined positional relationship to the irradiation system, for detecting the plurality of measurement beams from the substrate, and characterized in that in the irradiation system at least either one of the shape and size of at least one (S9) of the plurality of measurement beams on the surface of the object is smaller than at least either one of the shape and size of the other measurement beams (S1 to S8) on the surface of the object.
Moreover, with the first exposure method, by further having a step for detecting a position of the substrate (W) with respect to an imaging face of the pattern, using the at least one measurement beam (S9), the position of the substrate (W) with respect to the imaging face can be detected with even higher precision by the measurement beam. Furthermore, with the first exposure method, by further having a step for detecting an inclination of the substrate (W) with respect to an imaging face of the pattern, using the other measurement beams (S1 to S8), the inclination of the substrate with respect to the imaging face can be detected with high precision based on the information for the plurality of points on the surface of the substrate (W).
Furthermore, with the first exposure method, the at least one measurement beam (S9) is irradiated onto at least one flat portion formed beforehand on the substrate (W). Hence adverse effects due to the stepped portion can be efficiently prevented In this case, the flat portion includes a non-pattern area (100), onto which the pattern image of the mask (M) formed within each of a plurality of shot areas formed on the substrate (W) is not projected. Hence, adverse effects on the face position detection due to the stepped portion can be reliably prevented, enabling precise adjustment of the focal position, and as a result, enabling accurate exposure processing. Further, the first exposure method is preferably applied to a substrate for producing thin-film magnetic heads having a relatively large stepped portion.
A first production method for semiconductor devices according to the present invention is characterized by having a step for projection exposing a pattern on a mask (M) onto a substrate (W) by using the first exposure method. According to the first production method for semiconductor devices, semiconductor devices can be produced efficiently.
A production method for the first exposure apparatus according to the present invention is a production method for an exposure apparatus for exposing a substrate (W) by projecting onto the substrate a pattern image formed on a mask (M), characterized in that an irradiation system (4) for irradiating measurement beams (S1 to S9) onto a plurality of places on a substrate is provided, and a detection system (5) arranged in a predetermined positional relationship to the irradiation system, for detecting the plurality of measurement beams from the substrate is provided, and in the irradiation system at least either one of the shape and size of at least one (S9) of the plurality of measurement beams on the surface of the object is smaller than at least either one of the shape and size of the other measurement beams (S1 to S8) on the surface of the object. According to the production method for the first exposure apparatus, the apparatus can be easily produced, while maintaining at least one of the mechanical precision, electrical precision and optical precision required for the apparatus.
A second exposure method according to the present invention is a method for exposing a substrate by projecting onto a substrate CW) a pattern image formed on a mask (M), comprising steps for: irradiating measurement beams (S1 to S9) onto a plurality of places on a substrate; detecting the plurality of measurement beams from the substrate; and adjusting the relative position of the projected image of the pattern and the substrate based on the detection results, and characterized in that, in the step for detecting the measurement beams, a position of the substrate with respect to an imaging face of the pattern is detected by using at least one (S9) of the plurality of measurement beams, and an inclination of the substrate with respect to the imaging face of the pattern is detected by using the other measurement beams (S1 to S8). According to the second exposure method, while considering the inclination of the substrate (W), it becomes possible to adjust the focal position in a specific area on the substrate, enabling improvement in the precision of position adjustment. Hence, precise exposure processing can be performed.
The second exposure method is realized by a second exposure apparatus for exposing a substrate (W) by projecting onto the substrate a pattern image formed on a mask (M), having an irradiation system (4) for irradiating measurement beams (S1 to S9) onto a plurality of places on a substrate, and a detection system (5) arranged in a predetermined positional relationship to the irradiation system, for detecting the plurality of measurement beams from the substrate, and characterized in that the detection system detects the position of the substrate with respect to an imaging face of the pattern by using at least one of the plurality of measurement beams, and detects an inclination of the substrate with respect to the imaging face of the pattern by using the other measurement beams.
Furthermore, with the second exposure method, the at least one measurement beam (S9) is irradiated onto at least one flat portion formed beforehand on the substrate (W). Hence adverse effects due to the stepped portion can be efficiently prevented. Hence, due to the precise face position detection exposure processing can be performed with high precision. Further, the second exposure method is preferably applied to a substrate for producing thin-film magnetic heads having a relatively large stepped portion.
A second production method for semiconductor devices according to the present invention is characterized by having a step for projection exposing a pattern on a mask (M) onto a substrate (W) by using the second exposure method. According to the second production method for semiconductor devices, semiconductor devices can be produced efficiently.
A production method for the second exposure apparatus according to the present invention is a production method for an exposure apparatus for exposing a substrate (W) by projecting onto the substrate a pattern image formed on a mask (M), characterized in that an irradiation system (4) for irradiating measurement beams (S1 to S9) onto a plurality of places on a substrate is provided, and a detection system (5) arranged in a predetermined positional relationship to the irradiation system, for detecting the plurality of measurement beams from the substrate is provided, and the detection system detects the position of the substrate with respect to an imaging face of the pattern by using at least one (S9) of the plurality of measurement beams, and detects an inclination of the substrate with respect to the imaging face of the pattern by using the other measurement beams (S1 to S8). According to the production method for the second exposure apparatus, the apparatus can be easily produced, while maintaining at least one of the mechanical precision, electrical precision and optical precision required for the apparatus.
A third exposure method according to the present invention is an exposure method for sequentially exposing a plurality of shot areas on a substrate (W) as well as sequentially exposing a plurality of substrates, by projecting onto the substrate a pattern image formed on a mask (M), and is characterized by having steps for: mounting a substrate on a substrate holder (32) driven at the time of exposure processing; setting at least one time of; a time from mounting the substrate on the substrate holder until initiating exposure processing for the substrate, a time from completing exposure processing for the substrate using a first mask until initiating exposure processing for the substrate using a second mask different from the first mask, and a time from completing exposure processing for a first shot area on the substrate until initiating exposure processing for a second shot area to be exposed next; and executing exposure processing for the substrate based on the set time. According to the third exposure method, when divided areas on the plurality of substrates (W) are sequentially exposed, the interval time between each exposure can be set, thereby enabling prevention of deterioration in overlapping precision of layers due to thermal expansion of the substrate.
The third exposure method is realized by a third exposure apparatus for sequentially exposing a plurality of shot areas on a substrate (W) as well as sequentially exposing a plurality of substrates by projecting onto the substrate a pattern image formed on a mask (M), characterized by having: a substrate holder (32) for holding the substrate and driven at the time of exposure processing, and a control system (40) for setting at least one time of; a time from mounting the substrate on the substrate holder until initiating exposure processing for the substrate, a time from completing exposure processing for the substrate using a first mask until initiating exposure processing for the substrate using a second mask different from the first mask, and a time from completing exposure processing for a first shot area on the substrate until initiating exposure processing for a second shot area to be exposed next; and instructing the exposure processing for the substrate based on the set time.
Moreover, with the third exposure method, the at least one time is changed depending upon the layer on the substrate (W) to be subjected to the exposure processing, to optimally set the time for cooling the substrate which has been heated by the exposure processing, thereby preventing a drop in layer overlapping precision due to expansion and contraction of the substrate, enabling an improvement in exposure processing efficiency. Furthermore, with the third exposure method, by further having; a step for vacuum-attaching the substrate by means of the substrate holder, during the time from mounting the substrate (W) on the substrate holder (32) until the exposure processing for the substrate is initiated, and a step for releasing the vacuum-attached condition at the time of starting the exposure processing for the substrate, and vacuum-attaching the substrate again by means of the substrate holder, the difference in temperature between the substrate and the substrate holder is reduced by vacuum-attaching the substrate up until starting the exposure processing. Also by releasing the vacuum attachment once and then vacuum-attaching the substrate again, stress occurring in the substrate which is expanded and contracted by heating is released to thereby remove distortion occurring in the substrate. Consequently, face position detection and exposure processing can be precisely performed.
Also, with the third exposure method, by further having a step for adjusting the temperature of the substrate holder during the set time, the heat accumulated in the substrate holder is removed, and the temperature of the substrate holder is kept constant, so that the face position detection and the exposure processing can be performed accurately. Moreover, with the third exposure method, during the set time, by further having a step for keeping a stage on which the substrate is mounted stationary during the set time, time for decreasing the difference in temperature between the substrate and the substrate holder can be sufficiently ensured. Since the face position detection and exposure processing is performed after the deformation of the substrate due to heating has occurred, the face position detection and exposure processing can be performed accurately.
Preferably the third exposure method is applied to a substrate for producing a thin-film magnetic head having a relatively large stepped portion. In this case, at the time of exposure processing for forming a recording core of the thin-film magnetic head, by setting the at least one time longer than that for the exposure processing for forming other portions, the long exposure time requirement and the heat radiation after exposure of the recording core which is the part with the large stepped portion, can be reliably performed. Hence deterioration in overlapping precision of layers due to thermal expansion of the substrate can be prevented.
A third production method for semiconductor devices according to the present invention is characterized by having a step for projection exposing a pattern on a mask (M) onto a substrate (W) by using the third exposure method. According to the third production method for semiconductor devices, semiconductor devices can be produced efficiently.
A production method for the third exposure apparatus according to the present invention is a production method for an exposure apparatus for sequentially exposing a plurality of shot areas on a substrate (W) as well as sequentially exposing a plurality of substrates by projecting onto the substrate a pattern image formed on a mask (M), and is characterized by; providing a substrate holder (32) for holding the substrate and driven at the time of exposure processing, and a control system (40) for setting at least one time of; a time from mounting the substrate on the substrate holder until initiating exposure processing for the substrate, a time from completing exposure processing for the substrate using a first mask until initiating exposure processing for the substrate using a second mask different from the first mask, and a time from completing exposure processing for a first shot area on the substrate until initiating exposure processing for a second shot area to be exposed next; and instructing the exposure processing for the substrate based on the set time. According to the production method for the third exposure apparatus, the apparatus can be easily produced, while maintaining at least one of the mechanical precision, electrical precision and optical precision required for the apparatus.
A fourth exposure method according to the present invention is an exposure method for exposing a substrate (W) by projecting onto the substrate a pattern image formed on a mask (M), and is characterized by having steps for: selecting at least one measurement point to be used for detecting face positional information for the substrate from a plurality of measurement points, depending upon the condition of layers already formed on the substrate; detecting face positional information for the substrate based on positional information for the selected measurement point; and adjusting the relative position of the projected image of the substrate pattern and the substrate based on the detection results for the face positional information, and in the selection step, the plurality of measurement points are set beforehand for detecting the positional information for the substrate in a direction perpendicular to an imaging face of the pattern. According to the fourth exposure method, since at least one of the plurality of measurement points is selected according to the condition of the layers, by selecting a measurement point necessary and sufficient for detecting the face positional information, unnecessary detection of measurement points is prevented, enabling shortening of the processing time.
The fourth exposure method is realized by a fourth exposure apparatus for exposing a substrate (W) by projecting onto the substrate a pattern image formed on a mask (M), characterized by having: a selection device (40) for selecting at least one measurement point to be used for detecting face positional information for the substrate from a plurality of measurement points, depending upon the condition of layers already formed on the substrate; and a detection system (5) connected to the selection device for detecting the face positional information for the substrate based on the positional information for the selected measurement point, and in the selection device the plurality of measurement points are set beforehand for detecting the positional information for the substrate in a direction perpendicular to an imaging face of the pattern.
Moreover, with the fourth exposure method, when a stepped portion in the layer already formed on the substrate is large, the number of measurement points is increased, and when a stepped portion in the layer already formed on the substrate is small, the number of measurement points is decreased. As a result, when there is a big difference between the concave portion and the convex portion, the face positional information can be detected with high precision by using many measurement points, and when there is a small difference between the concave portion and the convex portion, a small number of measurement points is used. Hence, the processing time for detection can be shortened, enabling optimization of processing regardless of the size of difference between the concave portion and the convex portion. Furthermore, with the fourth exposure method, the measurement points are selected depending upon the information related to the layers on the substrate to be subjected to the exposure processing, enabling rapid and accurate selection of the measurement points.
Preferably the fourth exposure method is applied to a substrate for producing a thin-film magnetic head having a relatively large stepped portion. In this case, at the time of exposure processing for forming a recording core of the thin-film magnetic head, by selecting a larger number of measurement points than that for at the time of exposure processing for forming other portions, the face positional information can be detected with high precision, by using many measurement points with respect to the layer for forming the recording core.
A fourth production method for semiconductor devices according to the present invention is characterized by having a step for projection exposing a pattern on a mask (M) onto a substrate (W) by using the fourth exposure method. According to the fourth production method for semiconductor devices, semiconductor devices can be produced efficiently.
A production method for the fourth exposure apparatus according to the present invention is a production method for an exposure apparatus for exposing a substrate (W) by projecting onto the substrate a pattern image formed on a mask (M), characterized by providing: a selection device (40) for selecting at least one measurement point to be used for detecting face positional information for the substrate from a plurality of measurement points, depending upon the condition of layers already formed on the substrate; and a detection system (5) connected to the selection device for detecting the face positional information for the substrate based on the positional information for the selected measurement point, and in the selection device, the plurality of measurement points are set beforehand for detecting the positional information for the substrate in a direction perpendicular to an imaging face of the pattern. According to the production method for the fourth exposure apparatus, the apparatus can be easily produced, while maintaining at least one of the mechanical precision, electrical precision and optical precision required for the apparatus.